If you've been wondering why you still need an afternoon coffee on days you got a fair amount of zzz's, it might be because we actually need more than 8 hours of sleep per night.
Though we've been told all our lives that 8 hours is the recommended daily dose for adults, a sleep expert is now saying otherwise.
"In order to get a healthy eight hours of sleep, which is the amount that many people need, you need to be in bed for 8.5 hours," sleep scientist Daniel Gartenberg told Quartz.
"The standard in the literature is that healthy sleepers spend more than 90 percent of the time in bed asleep, so if you’re in bed for eight hours, a healthy sleeper might actually sleep for only about 7.2 hours."
"To see how much sleep you really need, Gartenberg said that when on holiday, try going to bed at your normal time and note what time you naturally wake up. "With no stressors or time to get up, you’ll just fall into a natural pattern, and that’s probably how much sleep you actually need."